module.exports = [
    '#define SHADER_NAME PHASER_DEFERRED_DIFFUSE_FS',
    '',
    'precision mediump float;',
    '',
    'struct Light',
    '{',
    '    vec3 position;',
    '    vec3 color;',
    '    float attenuation;',
    '    float radius;',
    '};',
    '',
    'const int kMaxLights = 50;',
    '',
    'uniform vec4 uCamera; /* x, y, rotation, zoom */',
    'uniform vec2 uResolution;',
    'uniform sampler2D uMainSampler; // gbuffer color',
    'uniform sampler2D uNormSampler; // gbuffer normal',
    'uniform vec3 uAmbientLightColor;',
    'uniform Light uLights[kMaxLights];',
    '',
    'void main()',
    '{',
    '    vec2 uv = vec2(gl_FragCoord.xy / uResolution);',
    '    vec3 finalColor = vec3(0.0, 0.0, 0.0);',
    '    vec4 gbColor = texture2D(uMainSampler, uv);',
    '    vec3 gbNormal = texture2D(uNormSampler, uv).rgb;',
    '    vec3 normal = normalize(vec3(gbNormal * 2.0 - 1.0));',
    '    vec2 res = vec2(min(uResolution.x, uResolution.y)) * uCamera.w;',
    '',
    '    for (int index = 0; index < kMaxLights; ++index)',
    '    {',
    '        Light light = uLights[index];',
    '        vec3 lightDir = vec3((light.position.xy / res) - (gl_FragCoord.xy / res), light.position.z);',
    '        vec3 lightNormal = normalize(lightDir);',
    '        float distToSurf = length(lightDir) * uCamera.w;',
    '        float diffuseFactor = max(dot(normal, lightNormal), 0.0);',
    '        float radius = (light.radius / res.x * uCamera.w) * uCamera.w;',
    '        float attenuation = clamp(1.0 - distToSurf * distToSurf / (radius * radius), 0.0, 1.0);',
    '        vec3 diffuse = light.color * gbColor.rgb * diffuseFactor;',
    '        finalColor += attenuation * diffuse;',
    '    }',
    '',
    '    vec4 colorOutput = vec4(uAmbientLightColor + finalColor, gbColor.a);',
    '    gl_FragColor = colorOutput;',
    '}'
].join('\n');
